植物萜类合成酶的进化研究

An Evolutionary Study of Plant Terpene Synthases

通过全面搜索和鉴定植物萜类合成酶基因家族的成员,我们重建了植物萜类合成酶的进化历史.研究发现植物萜类合成酶的进化历史和植物谱系的分歧历史一致.低等植物地钱和苔藓的基因组只编码一个萜类合成酶.从卷柏开始,萜类合成酶出现了基因重复和功能多样化,通过连续2次基因重复产生了3个萜类合成酶重复基因.其中2个重复基因的功能发生亚功能化,共同行使原来的功能;而第三个重复基因则发生了新功能化,转变为催化合成次生代谢萜类化合物,并且进一步分歧产生出萜类合成酶的其它4个亚家族.根据本研究构建的萜类合成酶进化树,我们推断上述2次基因重复事件发生在卷柏和其它陆地植物分歧之前的祖先植物谱系中.

Through thoroughly searching and identifying plant terpene synthases,we have reconstructed their evolutionary history.Our study shows that the evolutionary history of plant terpene synthases is concordant with the divergence history of land plants.Jungermannia subulata and Physcomitrella patens, two lower plant species,contained only one terpene synthase.Gene duplication and functional diversification of terpene synthases occurred at Selaginella moellendorfii,from which two successive gene duplication events generated three ancestral terpene synthase genes.Two of them subfunctionalized,and they together carried out their original function,while the third one neofunctionalized,and switched to the metabolism of secondary terpene synthesis.Moreover,four subfamilies of the terpene synthase gene family were generated by further gene duplications from the third duplicated terpene synthase gene copy.Based on the phylogenetic tree of plant terpene synthases,we infer that the two successive gene duplication events occurred in ancestral plant lineage prior to the divergence between S.moellendorfii and other land plants.